Work string tubing connection restoration

ABSTRACT

A hardfacing metal composition and method of restoring worn work string tubing by application of a hardfacing metal to the worn regions of the work string tubing.

The present disclosure is a divisional of U.S. application Ser. No.15/831,523 filed Dec. 5, 2017, (now U.S. Pat. No. 10,751,824; issued onAug. 25, 2020) which in turn claims priority on U.S. ProvisionalApplication Ser. No. 62/432,086 filed Dec. 9, 2016, which areincorporated herein by reference.

The present disclosure relates generally to metal alloys, particularlyto hardfacing metals, and more particularly to a method of restoringwork string tubing connections using a hardfacing metal alloy forimproving and/or extending the service life of work string tubing.

BACKGROUND ON THE DISCLOSURE

Work string tubulars enable drilling engineers to access a wellboreafter a well casing has been cemented and/or fracked. The constructionof work string tubes is different from that of drill pipe in that thebox and pin are integral upset regions within the tube itself. Drillpipe construction incorporates forged tool joints welded to a tube (seeFIG. 1 ). Work string tubes are integrally formed tube members that aretypically 2⅜″ and 2⅞″ in diameter and 30′ long; however, other sizestubes can be used (see FIG. 1 ). The work string tubes are generallyformed of high strength metal such as P110 (0.26-0.35% C, 0.17-0.37% Si,0.4-0.7% Mn, ≤0.02% P, ≤0.01% S, 0.8-1.1% Cr, ≤0.2% Ni, ≤0.2% Cu,0.15-0.25% Mn, ≤0.08% V, ≤0.02% Al, bal. Fe), a widely used grade tubehaving various thread connections with a yield strength of about 110,000psi, or PH6™ metal (a proprietary Hydril® connection). Work string tubesgenerally have a thinner metal thickness than standard drill pipe; thus,when work string tubes encounter excessive wear, the rehabilitation ofthe work string tubes is generally considered too difficult and wornwork string tubes are generally discarded.

During a typical work string operation, the work string tubeconnections' outside diameter is subjected to considerable wear. In workstring operations, the use of the work string tube is terminated whenthe upset outer diameter and inner diameter (i.e., upset wall thickness)calculates to less than an acceptable percent of the OEM torsionalcapacity for any specific type of work string tube. Generally, when theupset outer diameter and inner diameter calculates to less than 80% ofthe OEM torsional capacity for any specific type of work string tube,the work string tube is deemed unacceptable for further use in wellholeoperations; however, for different operations and types of work stringtubes, the value can be higher or lower than 80%. The tube body,however, which does not wear at the same rate as the upset connections,is typically still within specification and can typically be furtherused. However, because the connections between the work string tubeshave been worn to less than acceptable use standards, the work stringtube is downgraded to less than premium grade and is, therefore,unusable for further service in work string operations. Because of thesevere wear of the tubing connection upset area, many work string tubeslay dormant in pipe yards throughout the oilfield country. The upsetareas of the work string tubes are normally considered non-weldablebecause the welding arc used during a typically hardfacing operationgenerally penetrates through the thin wall of the work string tubeand/or damages the threading in the box of the work string tube andrenders the work string tube useless.

“Hardfacing” is an arc welding technique which involves applying a layerof hard material to a substrate for the purpose of increasing the wearand corrosion resistance of the substrate. The use of this technique hasincreased significantly over the recent years as the oil and gasindustries have come to recognize that the substrates of softer, lowercost material can be hardfaced to have the same wear and corrosionresistance characteristics as the more expensive substrates of a hardermaterial. Additionally, some existing substrates that have been rendereduseless in the industry can be hardfaced to restore and/or improve thewear and abrasion characteristics of the original substrates.

Hardfacing involves the deposition of a hard layer by arc welding orthermal spraying. Conventional weld hardfacing is accomplished byoxyfuel welding (OFW), gas tungsten arc welding (GTA), gas metal arcwelding (GMAW), shielded metal arc welding (SMAW) and flux-cored arcwelding (FCAW). Plasma transferred arc (PTA) hardfacing and laser beamhardfacing can also be used.

In view of the prior art, there remains a need for a process which cancircumvent the problems associated with hardfacing of the thin upsetareas of the pin and box connections of work string tubing so that usedwork string tubing can be reused.

SUMMARY OF THE DISCLOSURE

The present disclosure is directed to a repaired work string tube and anovel method for applying a hardfacing composition to work string tubing(such as work string tubing that was previously classified as less thanpremium grade) so that such work string tubing can be upgraded to beused again in work string operations. The box of the work string tubingis internally threaded for reception of a threaded pin member and thebox typically has a cylindrical outer surface. Likewise, the threadedpin member also typically has a cylindrical outer surface. The box andthreaded pin member generally having an outer diameter that is greaterthan the outer diameter of the main body of the work string tubing, andtypically have equal sized outer diameters; however, this is notrequired. As such, during use of the work string tubing, the box andthreaded pin member are exposed to a higher degree of wear. Once suchwear is calculated to result in the box and/or threaded pin memberhaving less than an acceptable percent of the OEM torsional capacity ofwork string tube (e.g., generally less than 80% of OEM diameter,typically 60%-95% of OEM diameter and all values and rangestherebetween), the worn section of work string tube is removed fromfurther service. In the past, such worn work string tube was discarded.The present disclosure is directed to a novel hardfacing process thatenables the worn regions of the box and threaded pin member to be builtup to at least its original OEM outer diameter without damaging thethreads in the box and/or the threads on the threaded pin member. Thenovel method includes applying a layer of hardfacing metal composition(e.g., welded) on the cylindrical outer surface of the box and/orthreaded pin member (and optionally on the pin upset area), therebyproviding a restored work string tubing which can withstand furtherabrasions and/or wear and be used in continued operation.

During work string operation, the work string tube connections' outsidediameter is subjected to considerable wear. When the upset wallthickness of the work string tube is less than an acceptable percent ofthe OEM torsional capacity for work string tube (e.g., less than 60%-90%and all values and ranges therebetween), the work string tube isrendered useless and cannot be used in further wellhole operations. Themethod of the present disclosure has been developed to enable the outersurface of the box and/or threaded pin member to be hardfaced to buildup such worn surfaces without damaging the thread in the box and/or onthe thread on the threaded pin member. The method of the presentdisclosure for the repair of the worn outer surface of the box of a workstring tube includes the steps of 1) optionally cutting off or otherwiseremoving a front end portion of the box, 2) applying a hardfacing metalto the worn region of the box to build up the outer diameter of the boxto at least its OEM outer diameter, and 3) optionally fixing the threadon the box at the front end region where a portion of the box was cutoff. Optional step three can occur prior to and/or after the step ofapplying a hardfacing metal to the box. Generally, about 0.1-2 inches(and all values and ranges therebetween) of the front end portion of thebox is removed prior to the hardfacing of the box, and typically about0.25-1.5 inches of the front end portion of the box is removed prior tothe hardfacing of the box. Generally, the amount of the front endportion of the box that is removed is less than 60% of the longitudinallength of the cavity of the box, and typically about 1%-60% (and allvalues and ranges therebetween) of the longitudinal length of the cavityof the box, and more typically less than 50% of the longitudinal lengthof the cavity of the box, and still more typically less than about 30%of the longitudinal length of the cavity of the box. Generally, thecutting of the box is by a mechanical means (e.g., saw blade, etc.), andnot by a cutting torch. The removal of a small portion of the front endportion of the box forms a clean and uniform front surface on the boxand removes any damaged, irregular or worn front edge surfaces orthreads located at the front end region of the box. After a portion ofthe front portion of the box has been removed, the front end of the boxcan be optionally further processed (e.g., ground, polished, deburred,front end of the threading repaired, etc.). Such optional furtherprocessing can occur prior to, during and/or after the hardfacing metalbeing applied to the worn outer surface of the box.

The box of the work string tube can be further processed prior toapplying a hardfacing metal to the worn outer surface of the box;however, this is not required. In one non-limiting embodiment, newthreads can optionally be in the cavity of the box prior to and/or afterthe hardfacing metal being applied to the worn outer surface of the box.As can be appreciated, new threads can be optionally cut in the cavityof the box after hardfacing metal has been partially or fully applied tothe worn outer surface of the box.

After the front end of the box has been cut and optionally furtherprocessed (e.g., new threads cut, ground, polished, deburred, etc.), thebox of the work string tube is generally positioned at a location sothat a hardfacing metal can be applied to the worn outer surface of thebox. Likewise, the threaded pin member of the work string tube isgenerally positioned at a location so that a hardfacing metal can beapplied to the worn outer surface of the threaded pin member. Theprocess of applying the hardfacing metal to the outer surface of thethreaded pin member and/or the box can be done by use of a conventionalwelder apparatus (e.g., arc welding machine).

During the application of the hardfacing metal to the outer surface ofthe threaded pin member and/or the box, a novel method for applying thehardfacing metal is typically used to minimize the amount of accumulatedheat in the box region and/or the threaded region of the threaded pinmember during the hardfacing operation so that the box and/or threadedpin member are not damaged during the hardfacing operation. In onenon-limiting embodiment, when hardfacing metal is applied to the wornregions of the outer surface of the box, the application of thehardfacing metal starts at the front end region of the box and continuestoward the end of the box. Generally, at the back end of the box, thebox tapers toward the main body of the work string tube; however, theexistence of a taper is not always present. This hardfacing method hasbeen found to reduce the amount of heat accumulated in the box duringthe hardfacing operation. It has been found that when too much heataccumulates in the box during a hardfacing operation, the box can softenand become disfigured, the threads in the cavity of the box can bedamaged, and/or holes from melted regions can form in thin areas of thebox. Any of these adverse events can result in permanent andirreversible damage to the box, thereby making further repair of the boxprohibitively costly and/or time consuming, thus not resulting in thefurther justification to attempt salvage of the worn work string tube.In another non-limiting embodiment, when hardfacing metal is applied tothe worn regions of the outer surface of the threaded pin member, theapplication of the hardfacing metal starts at the region just rearwardof the end of the threads and continues rearwardly toward the end of thethreaded pin member. Generally, at the back end of the threaded pinmember, the threaded pin member tapers toward the main body of the workstring tube; however, the existence of a taper is not always present.This hardfacing method has been found to reduce the amount of heataccumulated in the threaded region of the threaded pin member during thehardfacing operation. It has been found that when too much heataccumulates in the threaded region of the threaded pin member during ahardfacing operation, the thread can soften and become disfigured orotherwise be damaged. Any of these adverse events can result inpermanent and irreversible damage to the threaded pin member, therebymaking further repair of the threaded pin member prohibitively costlyand/or time consuming, thus not resulting in the further justificationto attempt salvage of the worn work string tube.

When the hardfacing metal is applied to the outer surface of thethreaded pin member and/or the box, the hardfacing generally terminatesat the beginning of the tapered region that transitions between the mainbody of the work string tube and the threaded pin member or the box(when such taper exists); however, this is not required. In onenon-limiting embodiment, the hardfacing metal is applied to less thanabout 70% of the outer surface of the tapered region, typically, thehardfacing metal is applied to about 0-70% (an all values and rangestherebetween) of the outer surface of the tapered region, more typicallythe hardfacing metal is applied to less than 50% of the outer surface ofthe tapered region, still more typically the hardfacing metal is appliedto less than about 20% of the outer surface of the tapered region, yetmore typically the hardfacing metal is applied to less than about 10% ofthe outer surface of the tapered region, and still yet more typicallythe hardfacing metal is applied to less than about 0% of the outersurface of the tapered region. When the hardfacing metal is not appliedto the tapered region, the application of the hardfacing metal can stopright at the beginning of the tapered region or be stopped at somedistance from the tapered region (e.g., 0.1-3 inches prior to thebeginning of the tapered region and all values and ranges therebetween).

In one non-limiting aspect of the present disclosure, there is provideda method for restoring a work string tubing connection. A portion of thefront end region of the box (e.g., 1 inch, etc.) can be removed and newthreads can optionally be cut prior to applying a hardfacing metal tothe outer surface of the box; however, this is not required. As can beappreciated, new threads can optionally be cut after the hardfacingoperation. The worn work string tube is transferred to a welding machine(e.g., arc welding machine), and the worn outside diameter of the box isrebuilt to within specification. Generally, the outer diameter of thebox after the hardfacing has been applied is 90-200% of the OEM diameterof the box (and all values and ranges therebetween), and typically theouter diameter of the box after the hardfacing has been applied is95-125% of the OEM diameter of the box, and more typically the outerdiameter of the box after the hardfacing has been applied is 100-110% ofthe OEM diameter of the box. The application of the hardfacing metal isstarted at the front end of the box and progresses to the end of the boxor to the tapered end of the box. This starting point of the applicationof the hardfacing metal and the direction of applying the hardfacingmetal to the box is used to reduce damage to the box during thehardfacing operation. By starting the application of the hardfacingmetal at the front end of the box, the incidence of burn-through in thebox (i.e., the creation of holes through the box) can be significantlyreduced or avoided. The type of hardfacing metal applied to the wornareas of the work string tube is non-limiting. Generally, thecomposition of the hardfacing metal is the same or similar to thecomposition of the work string tube; however, this is not required. Forexample, the hardfacing metal can have an as-welded hardness similar toP110 hardness for a weld string tube formed of P110; however, this isnot required. As can be appreciated, the chemical composition of suchhardfacing material can be the same as or different from the P110composition. The use of a welding material whose as-welded hardness issimilar to the P110 hardness will result in a wear life similar to theoriginal P110 connection. However, using a more abrasion-resistantmaterial such as, for example, Postle Industries' Duraband® NC, willresult in a wear life greater than the other softer metals. Duraband®(when used) has a hardness of from about 58 to about 62 Rockwell C (RC),whereas the original P110 material (when used) has a hardness of fromabout 26 to about 32 RC. Using Duraband® has many advantages, such asbeing casing-friendly. “Casing-friendly” is a term used in the oilfieldindustry to denote how any given hardfacing acts upon the casing duringdrilling operations. For example, a non-casing-friendly material such astungsten carbide causes excessive wear on a casing that lines thewellbore and can cause damage to the casing which can eventually cause ablowout. “Casing” is defined as a pipe or tube used as a lining for awell. P110 (when used without hardfacing) is not casing-friendly, and asimilar weld deposit (when used) will typically also not becasing-friendly.

In another and/or alternative non-limiting aspect of the presentdisclosure, during the application of the hardfacing material on thework string tube, the welding polarity is generally selected to be DCstraight polarity (electrode negative). Such a weld setting has beenfound to result in a shallower deposit of the hardfacing material on theouter surface of the work string tube than compared to the use of DCreverse polarity (electrode positive) that is common in hardfacingoperations. Also, the use of the DC straight polarity during thehardfacing operation results in little dilution and arc penetration intothe box. As such, when the DC straight polarity welding setting is used,the worn areas on the work string tube (that were previously considerednon-weldable due to the thin worn walls) were found to be restorableduring a hardfacing operation.

Generally, one layer (e.g., about 0.01″-0.40″ thick and all values andranges therebetween) of hardfacing material is sufficient to return thebox of the work string tube to its OEM outer diameter. As can beappreciated, more than one layer of hardfacing material can be appliedto the work string tube. In one non-limiting embodiment, two layers ofthe hardfacing material can be applied to the work string. Generally,the first layer has a thickness that is greater than or equal tosubsequent hardfacing layers; however, this is not required. In onenon-limiting example, the work string has a single layer of hardfacingmaterial applied to the box and/or threaded pin member of the workstring that is about 0.07-0.2 inches (e.g., 0.094-0.17 inches, etc.). Inanother non-limiting example, the work string has two layers ofhardfacing material applied to the box and/or threaded pin member of thework string wherein the first and second layers are about 0.05-0.2inches (e.g., 0.075-0.17 inches, etc.).

In another and/or alternative non-limiting aspect of the presentdisclosure, the longitudinal length of the box and/or threaded pinmember can be extended by using the hardfacing method of the presentdisclosure. The longitudinal length of the build-up is non-limiting anddepends on how much of the box or threaded pin member has been wornprior to the rebuilding procedure. For example, 3-4 inches of the frontend of the box (or some other length) may need to be removed due toexcessive damage to such region of the box. The amount of box removalmay result in the threaded end of a threaded pin member of another workstring not being able to be fully threaded into the shortened box. Assuch, the rear end of the box can be extended along the length of thework string by use of the hardfacing method of the present disclosure bya distance that would create a repaired box that has sufficient lengthto enable the threaded end of a threaded pin member of another workstring to be fully threaded into the repaired box. As with thehardfacing method for repairing the box, the hardfacing metal is firstapplied to the rear end of the box or at the region of the box thatbegins to taper downwardly toward the body of the work string, and thehardfacing material is continued to be applied rearwardly of the box toa distance that is to be used to extend the length of the box (e.g.,0.5-10 inches of box extension, etc.). After one or more layers ofhardfacing metal are used to extend the longitudinal length of the box,the box can be optionally further processed (e.g., ground, polished,deburred, etc.). Also, after the one or more layers of hardfacing metalare used to extend the longitudinal length of the box, the box can berethreaded so that new threads are extended into the extended region ofthe box; however, this is not required.

In another and/or alternative non-limiting aspect of the presentdisclosure, the entire area of the worn region on the box or threadedpin member can have a hardfacing material applied to such region;however, this is not required. The application of a hardfacing materialon the complete worn region will yield a much greater contact area onthe box and/or threaded pin member and thereby potentially reduce thewear rate on the box or pin as compared to a box or pin that onlyincludes hardfacing material on a smaller region of the box or pin.Additionally, rebuilding the outer diameter of the box or pin to thesame or slightly greater than the OEM diameter can be used to allowfinishing tools, etc. to clear a path to operate.

In another and/or alternative non-limiting aspect of the presentdisclosure, there is provided a hardfacing metal alloy which isparticularly useful for use as a metal surfacing on materials subjectedto mechanical stresses (e.g., abrasions, wear, etc.) such as, but notlimited to, work string tubing. The hardfacing metal of the presentdisclosure can be welded to a surface under various types of gas (e.g.,carbon dioxide, argon, carbon dioxide-argon mixture, etc.),self-shielded (open arc) tubular wire, submerged arc electrode, etc. Thehardfacing metal can be applied by use of a solid metal electrode, ametal cored electrode, or a flux cored electrode.

The hardfacing metal composition can include a combination of carbon,manganese, silicon, chromium, niobium, molybdenum, iron, nickel, etc. inproportional amounts wherein each component is believed to have aspecific function. The carbon in the hardfacing metal is believed toinfluence the hardness level of the hardfacing metal. Generally, thecarbon content of the hardfacing metal is at least about 0.05 weightpercent of the hardfacing metal and less than about 1.5 weight percent.The manganese in the hardfacing metal is believed to function as adeoxidizer and to also reduce or prevent hot cracking of the hardfacingmetal. Generally, the manganese content of the hardfacing metal is atleast about 0.5 weight percent of the hardfacing metal and less thanabout 2 weight percent. The silicon in the hardfacing metal is believedto function as a deoxidizer for the hardfacing metal. Generally, thesilicon content of the hardfacing metal is at least about 0.2 weightpercent of the hardfacing metal and less than about 1.2 weight percent.The chromium in the hardfacing metal is believed to affect hardenabilityof the hardfacing metal. Generally, the chromium content of thehardfacing metal is at least about 1.5 weight percent of the hardfacingmetal and less than about 9.5 weight percent. The niobium (when used) inthe hardfacing metal is believed to increase the volume of niobiumcarbides formed in the hardfacing metal. Generally, the niobium contentof the hardfacing metal is at least about 4 weight percent of thehardfacing metal and less than about 7 weight percent. The molybdenum(when used) in the hardfacing metal is believed to affect thehardenability and the volume of molybdenum carbides formed of thehardfacing metal. Generally, the molybdenum content of the hardfacingmetal is at least about 0.5 weight percent of the hardfacing metal andless than about 2 weight percent. The iron in the hardfacing metal isused to obtain the desired iron content of the metal alloy. Thehardfacing metal is generally formed of a majority of iron (e.g., 80-95weight percent); however, this is not required. Nickel (when used) isbelieved to add strength and hardness to the hardfacing metal.Generally, the nickel content of the hardfacing metal, when used, is atleast about 0.05 weight percent of the hardfacing metal and less thanabout 3 weight percent. As can be appreciated, the composition of thehardfacing metal can include other and/or alternative components toreduce or prevent sensitization of the hardfacing metal (e.g.,nitrogen), to affect the corrosion resistance of the hardfacing metal,affect the strength, toughness and ductility of the hardfacing metal(e.g., nickel), and/or to increase the resistance of the hardfacingmetal to tempering and/or to prevent sensitization of the hardfacingmetal (e.g., vanadium); however, this is not required.

The hardfacing metal can be formed by blending and/or mixing one or morecomponents together, which can then be melted by a heat source (such asa furnace) and formed into a single, blended hardfacing metal material;however, this is not required. The hardfacing metal can be in the formof a wire, cored wire, etc. In one non-limiting configuration, thehardfacing metal is formed in a wire having a diameter of about 0.045″;however, other wire sizes can be used.

The hardfacing metal can be applied to a surface of a substrate (e.g.,work string tubing) by welding; however, other or alternative techniquescan be used. In one non-limiting configuration, the polarity iselectrode negative (spray mode); however, the polarity can also oralternatively be electrode positive (short circuit mode). The hardfacingmetal to the work string tubing is typically applied under a shieldinggas such as, for example, argon and/or carbon dioxide; however, this isnot required. The ratio of argon to carbon dioxide is non-limiting, andcan be from about 3:1 to about 9:1; however, this is not required. Ascan be appreciated, other shielding gasses (when used) can be used.

In one non-limiting example, the hardfacing material can include acombination of carbon, manganese, silicon, chromium, iron, molybdenumand/or niobium. In one non-limiting embodiment, the hardfacing materialincludes by weight:about 0.5% to about 2.5% carbon (and all values andranges therebetween), about 0.01% to about 2% manganese (and all valuesand ranges therebetween), about 0.01% to about 2% silicon (and allvalues and ranges therebetween), about 4% to about 11% chromium (and allvalues and ranges therebetween), about 3% to about 9% niobium (and allvalues and ranges therebetween), and at least about 70% iron (e.g., thebalance iron); and optionally include impurities and trace elements. Thehardfacing material has a hardness of about 50-70 Rc (ISO 6508-1) (andall values and ranges therebetween), and typically about 55-65 Rc. Onespecific hardfacing electrode that can be used to form such hardfacingmetal is set forth in Table 1.

TABLE 1 (Postalloy Duraband ®) Component General Range SpecificFormulation Carbon    1-2 wt. % 1.2 wt. % Manganese 0.5-1.5 wt. % 0.9wt. % Silicon 0.5-1.5 wt. % 0.9 wt. % Chromium    6-10 wt. %   8 wt. %Niobium    4-8 wt. %   6 wt. % Iron   75-88 wt. % Balance

The non-limiting welding parameters used to apply a hardfacing metal tothe outer surface of a pin or box or a work string tube using theelectrode in Table 1 is set forth in Table 2:

TABLE 2 Wire Size 0.045” Polarity Electrode Negative (Spray Mode)Shielding Gas 75% Argon-25% CO₂ Amperage 180 Voltage  31 Torch Angle 16°Torch Offset    1” Stickout 5/8” Oscillation 3/8” Oscillation Count60/min Rotation 1’-55”/revolution Preheat Temperature  70° F. InterpassTemperature 700° F.

In a second non-limiting example, the hardfacing material can include acombination of carbon, manganese, silicon, chromium, iron and/ormolybdenum. In one non-limiting example of the second non-limitingembodiment, the hardfacing composition includes by weight:about 0.01% toabout 0.25% carbon (and all values and ranges therebetween), about 0.5%to about 2.5% manganese (and all values and ranges therebetween), about0.01 percent to about 2% silicon (and all values and rangestherebetween), about 1% to about 3.5% chromium (and all values andranges therebetween), about 0.01% to about 2% molybdenum (and all valuesand ranges therebetween), and at least about 85% iron (e.g., the balanceiron); and optionally include impurities and trace elements. Thehardfacing material has a hardness of about 25-40 Rc (ISO 6508-1) (andall values and ranges therebetween), and typically about 28-35 Rc. Onespecific hardfacing electrode that can be used to form such hardfacingmetal is set forth in Table 3.

TABLE 3 (Postalloy TubeWeld 110 ™) Component General Range SpecificFormulation Carbon 0.08-0.14 wt. % 0.1 wt. % Manganese     1-2 wt. % 1.5wt. % Silicon    0.2-1 wt. % 0.5 wt. % Chromium    1.5-3 wt. % 2.5 wt. %Molybdenum  0.6-1.4 wt. %   1 wt. % Iron  91-96.62 wt. % Balance

The non-limiting welding parameters used to apply a hardfacing metal tothe outer surface of a pin or box or a work string tube using theelectrode in Table 3 is set forth in Table 4:

TABLE 4 Wire Size 0.045” Polarity Electrode Positive (Short CircuitMode) Shielding Gas 90% Argon-10% CO₂ Amperage 235 Voltage  21.5 TorchAngle 11.5° Torch Offset    1” Stickout 1/2” Oscillation 3/8”Oscillation Count 100/min Rotation 1’-55”/revolution Preheat Temperature 87° F. Interpass Temperature 650° F.

In a third non-limiting embodiment, the hardfacing material can includea combination of carbon, manganese, silicon, chromium, iron, and/ormolybdenum. In one non-limiting example of the third non-limitingembodiment, the hardfacing composition includes by weight:about 0.01% toabout 1.2% carbon (and all values and ranges therebetween), about 0.01%to about 1.5% manganese (and all values and ranges therebetween), about0.01% to about 1.5% silicon (and all values and ranges therebetween),about 1.5% to about 4% chromium (and all values and rangestherebetween), and about 0.01% to about 3% molybdenum (and all valuesand ranges therebetween), and at least about 85% iron (e.g., the balanceiron); and optionally include impurities and trace elements. Thehardfacing material has a hardness of about 25-40 Rc (ISO 6508-1) (andall values and ranges therebetween), and typically about 28-35 Rc. Onespecific hardfacing electrode that can be used to form such hardfacingmetal is set forth in Table 5.

TABLE 5 (Postalloy 2891) Component General Range Specific FormulationCarbon  0.04-0.2 wt. % 0.08 wt. % Manganese    0.4-1 wt. %  0.7 wt. %Silicon  0.2-0.7 wt. % 0.35 wt. % Chromium    1.8-3 wt. % 2.25 wt. %Molybdenum  0.4-1.8 wt. %   1 wt. % Iron  90-97.16 wt. % Balance

The non-limiting welding parameters of the alloy composition of thethird embodiment are presented in Table 6:

TABLE 6 Wire Size 0.045” Polarity Electrode Negative (Spray Mode)Shielding Gas 75% Argon-25% CO₂ Amperage 220 Voltage  21.5 Torch Angle11.5° Torch Offset    1” Stickout 1/2” Oscillation 3/8” OscillationCount 100/min Rotation 1’-55”/revolution Preheat Temperature  70° F.Interpass Temperature 690° F.

Generally, only one layer of the hardfacing metal is applied to theouter surface of the box and/or threaded pin member of the work stringtube; however, this is not required. The weld bead of the hardfacingmetal composition can be about 3/32″ to about ¼″ thick; however, this isnot required.

During the application of the hardfacing metal to the worn surface ofthe work string tube, the work string tube can be rotated about itslongitudinal axis; however, this is not required.

In one non-limiting aspect of the present disclosure, there is provideda method for improving use a work string tubing in well operations, themethod comprising: 1) using a work string tubing in a wellbore toservice a well until the workstring is worn and is no longer approved tobe used in the well (e.g., outer diameter of box and/or threaded pinmember has been worm to 80% or less of OEM diameter, etc.); 2) removingthe worn work string tubing from the wellbore once the upset outerdiameter and/or inner diameter calculates to be less than an acceptablepercent of the OEM maximum torsional capacity for the work string tube(e.g., less than about 80%, etc.); 3) optionally disconnecting the boxand pin of adjacently connected worn work string tubes; 4) optionallyremoving an end portion of the box of the worn work string tube and/orremoving a damaged or worn end of the threaded portion of the threadedpin member; 5) optionally repairing or rethreading the thread in theworn box after the removal of the end portion of the box and/orrepairing or rethreading the thread of the threaded portion of thethreaded pin member; 6) applying a hardfacing metal to the box of theworn work string tube such that the outer diameter of the box is at orslightly greater than the OEM outer diameter of the box (e.g., 90-120%of the OEM diameter of the box and all values and ranges therebetween)and/or applying a hardfacing metal to the threaded pin member of theworn work string tube such that the outer diameter of the pin is at orslightly greater than the OEM outer diameter of the pin (e.g., 90-120%of the OEM diameter of the threaded pin member and all values and rangestherebetween); 7) optionally extending the longitudinal length of thebox and/or threaded pin member by applying hardfacing metal to the endof the box and/or threaded pin member; 8) optionally rethreading the boxand/or threaded pin member after the hardfacing metal has been appliedto the box and/or threaded pin member; 9) optionally grinding,polishing, and/or deburring the box and/or threaded pin member after thehardfacing metal has been applied to the box and/or threaded pin member;10) optionally reconnecting the hardfaced box of the work string tube toan OEM threaded pin member or rebuilt threaded pin member of anotherwork string tube; and 11) inserting the connected hardfaced work stringtube into a well bore to further service the well.

In another and/or alternative non-limiting aspect of the presentdisclosure, there is provided a method of applying a hardfacing metalcomposition to a surface of a work string tube comprising: a) selectinga worn work string tube; and, b) applying a hardfacing metal compositionat least partially on a worn surface of the work string tube.

It is one non-limiting object of the present disclosure to provideimproved materials and methods for producing viable work string tubinghaving restored integrity and which offers savings in work string life.

It is another and/or alternative non-limiting object of the presentdisclosure to provide a hardfacing metal composition having improvedabrasion-resistance which can be applied to work string tubing.

It is another and/or alternative non-limiting object of the presentdisclosure to provide a hardfacing metal composition suitable forrestoring worn work string tubing.

It is another and/or alternative non-limiting object of the presentdisclosure to provide a hardfacing metal composition havingabrasion-resistance characteristics, which can be applied to an outersurface of worn work string tubing, is capable of minimizing casing wearin a wellbore hole, and maximizes the wear resistance of the work stringtubing.

It is another and/or alternative non-limiting object of the presentdisclosure to provide a method for applying a hardfacing metalcomposition to worn work string tubing at a work string tubing operationsite, thereby extending the life of the work string tubing and improvingthe throughput at the work string tubing operation site.

It is another and/or alternative non-limiting object of the presentdisclosure to provide a method for repairing and reusing worn workstring tube in well operations.

These and other objects and advantages will become apparent to thoseskilled in the art upon reading and following the description takentogether with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference may now be made to the drawings which illustrate variousnon-limiting embodiments that the disclosure may take in physical formand in certain parts and arrangement of parts wherein:

FIG. 1 is an illustration showing the differences between drill pipe andwork string tubing;

FIG. 2 is an illustration showing the process of hardfacing a worn workstring tube in accordance with one non-limiting aspect of the presentdisclosure;

FIG. 3 is an illustration showing the process of work string tubingrestoration in accordance with one non-limiting aspect of the presentdisclosure;

FIG. 4 is an illustration showing the hardfacing process with DCpolarity (electrode negative) and weld bead direction from the threadedend progressing to the tapered end of the work string tubing;

FIG. 5 is an illustration showing the non-oscillation hardfacing processwith DC polarity (electrode negative) and weld bead direction from thethreaded end progressing to the tapered end with spiral configuration;

FIG. 6 is an illustration showing the oscillating hardfacing processwith DC polarity (electrode negative) and weld bead direction from thethreaded end progressing to the tapered end with spiral configuration;

FIG. 7 is an illustration showing the hardfacing process with DCpolarity and weld bead direction from the threaded end progressing tothe tapered end using 360°+step-overs;

FIG. 8 is an illustration showing the hardfacing process with a prouddiameter above the original diameter;

FIG. 9 is an illustration showing the hardfacing of the full length ofthe upset area with a second layer at or near the tapered end of theupset area;

FIG. 10 is a graphical representation showing microhardness valuesversus inches in depth below the surface of the hardfacing of Duraband®NC;

FIG. 11 is a graphical representation showing microhardness valuesversus inches in depth below the surface of the hardfacing of Postalloy®2891;

FIG. 12 is a graphical representation showing microhardness valuesversus inches in depth below the surface of the hardfacing of Postalloy®Tubewell 110™;

FIG. 13 is a cross-sectional illustration of work string tubing;

FIG. 14 is a table showing various coupling dimensions of a work stringtubing having four threads per inch; and,

FIG. 15 is a table showing various coupling dimensions of a Hydril PH6tubing connection having six threads per inch.

DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENTS

The present disclosure is directed to a repaired work string tube and anovel method for applying a hardfacing composition to work string tubing(such as work string tubing that was previously classified as less thanpremium grade) so that the work string tubing can be used again in workstring operations. In particular, the present disclosure is directed toa novel hardfacing process that enables the worn regions of the boxand/or threaded pin member of a work string tube to be built up to atleast its original OEM outer diameter without damaging the threads inthe box and/or the threads on the threaded pin member. The novel methodincludes applying a layer of hardfacing metal composition (e.g., welded)on the cylindrical outer surface of the box and/or threaded pin member(and optionally on the pin upset area), thereby providing a restoredwork string tubing which can withstand further abrasions and/or wear andbe used in continued operation.

Work string tubes are constructed differently from drill pipe, and thusare typically less durable. As illustrated in FIG. 1 , drill pipes 100typically include forged tool joints 110, 120 welded to the body of thedrill pipe by a welded connection 130. These types of joints can be usedsince the walls of the drill pipe are sufficiently thick to enable astrong weld connection to be formed between the body of the drill pipeand the joints. Work string tubes 200 generally have thinner walls thanthe drill pipes, thus the joints 210, 220 are typically integrallyformed with the body 202 of the work string tube to form a sufficientlystring connection between the body and the joint. These work stringtubes typically have a diameter of about 2⅜″ to 2⅞″ and are typicallyabout 30′ long; however, other sizes tubes can be used. As known in theart, joint 210 located at one end of the work string tube (known as the‘box’) and includes a threaded cavity (not shown), and joint 220 that islocated at the other end of the work string tube is known as thethreaded pin member. The OEM outer diameter of joints 210 and 220 aregreater than the OEM outer diameter of the body 202 of the work stringas illustrated in FIG. 1. From the front end 212 of the box to thebeginning 216 of the tapered region 214 of the box, the outer diameterof the box is generally constant. Generally, the longitudinal length ofthe constant diameter portion of the box represents about 60-98% of thetotal longitudinal length of the box. The tapered region 214 isillustrated as tapering at a generally constant angle from the beginning216 of the taper portion to the end 218 of the taper portion. As alsoknown in the art, joint 220 located at the other end of the work stringtube (known as the ‘threaded pin member’) and includes a threadedportion 222 that terminates into the front wall of the upset portion 224of the threaded pin member. From the front end 226 of the upset portionto the beginning 228 of the tapered region 230 of the box, the outerdiameter of the upset portion is generally constant. Generally, theouter diameter of this portion of the upset portion is the same as theouter diameter of the box that is located between the front end 212 ofthe box to the beginning 216 of the tapered region 214; however, this isnot required. The threaded portion 222 generally has an outer diameterthat is less than the outer diameter of the upset portion 224 asillustrated in FIG. 1 . The tapered region 230 is illustrated astapering at a generally constant angle from the beginning 228 of thetaper portion to the end 232 of the taper portion. Generally, thelongitudinal length of the constant diameter portion of the upsetportion represents about 50-80% of the total longitudinal length of theupset portion.

The method for using and maintaining work string tubing in welloperations in accordance with the present disclosure includes the stepsof 1) using a work string tubing in a wellbore to service a well untilthe work string tubing is worn and is no longer approved to be used inthe well (e.g., outer diameter of box and/or upset portion of thethreaded pin member has been worn to 80% or less (50-79.99%) of OEMdiameter, etc.); 2) removing the worn work string tubing from thewellbore once the upset outer diameter and/or inner diameter calculatesto be less than an acceptable percent of the OEM maximum torsionalcapacity for the work string tube (e.g., less than about 80% or less(50-79.99%), etc.); 3) optionally disconnecting the box and pin ofadjacently connected worn work string tubes; 4) applying a hardfacingmetal to the box of the worn work string tube such that the outerdiameter of the box is at or slightly greater than the OEM outerdiameter of the box (e.g., 90-150% of the OEM diameter of the box andall values and ranges therebetween [i.e., 95%-110%, etc.]) and/orapplying a hardfacing metal to the worn upset portion of the threadedpin member such that the outer diameter of the upset portion is at orslightly greater than the OEM outer diameter of the upset portion (e.g.,90-150% of the OEM diameter of the box and all values and rangestherebetween [i.e., 95%-110%, etc.]); 5) optionally grinding, polishing,and/or deburring the box and/or threaded pin member prior to, during,and/or after the hardfacing metal has been applied to the box and/orthreaded pin member; 6) optionally reconnecting the hardfaced box of thework string tube to an OEM threaded pin member or a rebuilt threaded pinmember of another work string tube; and 7) inserting the connectedhardfaced work string tube into a well bore to further service the well.

The method step 4) of applying a hardfacing metal to the box of the wornwork string tube and/or applying a hardfacing metal to the threaded pinmember of the worn work string tube includes a novel method of a)optionally removing an end portion of the box of the worn work stringtube and/or removing a damaged or worn end of the threaded portion ofthe threaded pin member; b) optionally repairing or rethreading thethread in the worn box after the removal of the end portion of the boxand/or repairing or rethreading the thread of the threaded portion ofthe threaded pin member; c) applying a hardfacing metal to the boxand/or applying a hardfacing metal to the upset portion of the threadedpin member.

Referring now to FIG. 3 , there is illustrated a work string tubingwherein the box is at the OEM diameter (A), the box is worn and is lessthan the OEM diameter (B), and the box has been repaired by hardfacingin accordance with the present disclosure and has an outer diameter thatis equal to the OEM diameter (C). As illustrated in the third diagram ofFIG. 3 , the hardfacing metal was applied to the complete region of thebox that has a constant outer diameter. As also illustrated in the thirddiagram of FIG. 3 , the hardfacing metal was applied to only a portionof the tapered region 214 of the box. Generally, about 0-50% (and allvalues and ranges therebetween) of the tapered region is coated with thehardfacing metal, and typically about 0-20% of the tapered region iscoated with the hardfacing metal, unless the longitudinal length of thebox is to be extended.

Referring now to FIGS. 2 and 4-9 , several different non-limitinghardfacing processes are illustrated that can be used to applyhardfacing metal to the box and/or the threaded pin member. In each oneof the illustrated hardfacing processes, the direction of theapplication of the hardfacing metal on the box or the upset portion ofthe threaded pin member is toward the tapered region of the work stringtubing. The novel method for applying the hardfacing metal to the box orthe upset portion of the threaded pin member to repair worn portions ofthe work string so that the work string can be reused in accordance withthe present disclosure, while minimizing or preventing 1) the softeningand/or disfiguring of the box, 2) damage to the threads in the cavity ofthe box, 3) formation of holes or other damage in thin or worn areas ofthe box, 4) damage to the threaded region of the threaded pin member,and/or 5) any of type of damage to the box or threaded pin member,includes the steps of i) optionally cutting off or otherwise removing afront end portion of the box (e.g., removing a damaged and/or overlyworn front end portion of the box, etc.) and/or removing a front portionof the threaded region of the threaded pin member (e.g., removing adamaged and/or overly worn front end portion of the threaded region ofthe threaded pin member, etc.), ii) applying one or more layers of ahardfacing metal to the outer surface of the box in a direction from thefront end of the box towards the end of the box or the tapered end ofthe box, and/or applying a hardfacing metal to the outer surface of theupset portion of the threaded pin member in a direction from the frontend of the upset portion to the end of the threaded pin member or thetapered end of the threaded pin member, iii) optionally furtherprocessing the box and/or threaded pin member by grinding, polishing,deburring, and/or heat treating the box and/or threaded pin member afterthe hardfacing metal has been applied to the box and/or threaded pinmember, and iv) optionally repairing the threads or rethreading thethreads in the cavity of the box and/or on the threaded region of thethreaded pin member after the hardfacing metal has been applied to thebox and/or threaded pin member.

When the box and/or threaded pin member of the work string tubing needsto be lengthened due to the removing of a portion of the front end ofthe box and/or the removing of the front end portion of the threadedregion of the threaded pin member, the novel method for applying thehardfacing metal to the box or the upset portion of the threaded pinmember in accordance with the present disclosure can optionally be usedto lengthen the box and/or threaded pin member of the work stringtubing. The method includes the steps of I) optionally cutting off orotherwise removing a front end portion of the box (e.g., removing adamaged and/or overly worn front end portion of the box, etc.) and/orremoving a front portion of the threaded region of the threaded pinmember (e.g., removing a damaged and/or overly worn front end portion ofthe threaded region of the threaded pin member, etc.), II) optionallyapplying one or more layers of a hardfacing metal to the outer surfaceof the box at a portion between the front end of the box and thebeginning of the tapered region or the end of the box that has notapered region in a direction from the front end of the box towards theend of the box or the tapered end of the box, and/or applying ahardfacing metal to the outer surface of the upset portion of thethreaded pin member between the front end of the upset portion and thebeginning of the tapered region or the end of the upset portion that hasno tapered region in a direction from the front end of the upset portionto the end of the threaded pin member or the tapered end of the threadedpin member, III) applying one or more layers of a hardfacing metal tothe outer surface of the box that includes the beginning of the taperedregion or the end of the box that has no tapered region and continues tocover all or a portion of the tapered region and/or a portion of thebody of the work string tubing (0.001-5% and all values and rangestherebetween of the longitudinal length of the body), and/or applyingone or more layers of a hardfacing metal to the outer surface of theupset portion that includes the beginning of the tapered region or theend of the upset portion that has no tapered region and continues tocover all or a portion of the tapered region and/or a portion of thebody of the work string tubing (0.001-5% and all values and rangestherebetween of the longitudinal length of the body), IV) optionallyfurther processing the box and/or threaded pin member by grinding,polishing, deburring, and/or heat treating the box and/or threaded pinmember after the hardfacing metal has been applied to the box and/orthreaded pin member, V) optionally extending the longitudinal length ofthe cavity of the box by cutting further into the existing box and/orextended box and/or lengthen the threaded region of the threaded pinmember by cutting into the front face of the existing unset portion ofthe threaded pin member, and VI) optionally repairing the threads orrethreading the threads in the cavity of the box and/or on the threadedregion of the threaded pin member after the hardfacing metal has beenapplied to the box and/or threaded pin member to extend the longitudinallength of the box and/or threaded pin member.

Referring again to FIG. 2 , there is illustrated a work string tubing200 wherein the joint 210 or box has a hardfacing metal 320 applied tothe outer surface of the box. Although not shown, one skilled in the artwould understand that the threaded pin member could be hardfaced insteadof the box. A welding torch 300 powered by a welding power supply 310 isused to melt a hardfacing electrode onto the outer surface of the box.As illustrated by the arrow, the welding torch is moved in the directiontoward the tapered region of the box as the hardfacing metal is appliedto the outer surface of the box. FIG. 2 illustrates that only a portionof the outer surface of the box has hardfacing material applied to thebox near the tapered end of the box. However, it can be appreciated thatthe complete outer surface of the box can be coated with a hardfacingmetal as illustrated in the third picture of FIG. 3 . The ribbons ofhardfacing that are applied to the outer surface of the box areillustrated as being positioned directly adjacent to one another suchthat the edges of the ribbons of hardfacing metal are on contact withone another. The application of the hardfacing can be applied by usingDC polarity (electrode negative). In one non-limiting arrangement, thewidth of the hardfacing bead applied to the outer surface of the box isabout 0.5-2 inches (e.g., 1 inch, etc.) and has a thickness of about0.04-0.3 inches (e.g., 0.094 inches, etc.). During the application ofthe hardfacing metal to the outer surface of the box, 1) the electrodecan be moved along the longitudinal length and/or about the outersurface of the box or upset portion while the work string tubing ismaintained in position, 2) the electrode can be moved along thelongitudinal length and/or about the outer surface of the box or upsetportion while the work string tubing is rotated and/or moved along itslongitudinal axis, or 3) the electrode can maintained stationary whilethe work string tubing is rotated and/or moved along its longitudinalaxis.

Referring now to FIG. 4 , there is illustrated a work string tubing 200wherein the joint 210 or box has a hardfacing metal 320 applied to theouter surface of the box. Although not shown, one skilled in the artwould understand that the threaded pin member could be hardfaced insteadof the box. A welding torch 300 powered by a welding power supply 310 isused to melt a hardfacing electrode onto the outer surface of the box.As illustrated by the arrow, the welding torch is moved in the directiontoward the tapered region of the box as the hardfacing metal is appliedto the outer surface of the box. FIG. 4 illustrates that the hardfacingmetal application started at the front end of the box and is progressingtoward the tapered region of the box. The ribbons of hardfacing metalthat are applied to the outer surface of the box are illustrated asbeing positioned directly adjacent to one another such that the edges ofthe ribbons of hardfacing metal are on contact with one another. Theapplication of the hardfacing metal can be applied by using DC polarity(electrode negative). In one non-limiting arrangement, the width of thehardfacing bead applied to the outer surface of the box is about 0.5-2inches (e.g., 1 inch, etc.) and has a thickness of about 0.04-0.3 inches(e.g., 0.094 inches, etc.). During the application of the hardfacingmetal to the outer surface of the box, 1) the electrode can be movedalong the longitudinal length and/or about the outer surface of the boxor upset portion while the work string tubing is maintained in position,2) the electrode can be moved along the longitudinal length and/or aboutthe outer surface of the box or upset portion while the work stringtubing is rotated and/or moved along its longitudinal axis, or 3) theelectrode can maintained stationary while the work string tubing isrotated and/or moved along its longitudinal axis.

Referring now to FIG. 5 , there is illustrated a work string tubing 200wherein the joint 210 or box has a hardfacing metal 320 applied to theouter surface of the box. Although not shown, one skilled in the artwould understand that the threaded pin member could be hardfaced insteadof the box. A welding torch 300 powered by a welding power supply 310 isused to melt a hardfacing electrode onto the outer surface of the box.As illustrated by the arrow, the welding torch is moved in the directiontoward the tapered region of the box as the hardfacing metal is appliedto the outer surface of the box. FIG. 5 illustrates that the hardfacingmetal application started at the front end of the box and is progressingtoward the tapered region of the box. The ribbons of hardfacing metalthat are applied to the outer surface of the box are illustrated asbeing spaced from one another such that the edges of a ribbon ofhardfacing metal does contact with one another. In such a hardfacingprocess, multiple ribbons of hardfacing metal will need to be applied tothe box to fully cover the outer surface of the box at the regionlocated between the front end of the box and the tapered region of thebox. The application of the hardfacing metal can be applied by using DCpolarity (electrode negative). In one non-limiting arrangement, thewidth of the hardfacing bead applied to the outer surface of the box isabout 0.5-2 inches (e.g., 1 inch, etc.) and has a thickness of about0.04-0.3 inches (e.g., 0.094 inches, etc.). During the application ofthe hardfacing metal to the outer surface of the box, 1) the electrodecan be moved along the longitudinal length and/or about the outersurface of the box or upset portion while the work string tubing ismaintained in position, 2) the electrode can be moved along thelongitudinal length and/or about the outer surface of the box or upsetportion while the work string tubing is rotated and/or moved along itslongitudinal axis, or 3) the electrode can maintained stationary whilethe work string tubing is rotated and/or moved along its longitudinalaxis.

Referring now to FIG. 6 , the application of applying the hardfacingmetal to the box of the work string tubing is similar to the hardfacingprocess illustrated in FIG. 5 except that the width of the hardfacingmetal ribbon is wider and spaced farther apart.

Referring now to FIG. 7 , there is illustrated a work string tubing 200wherein the joint 210 or box has a hardfacing metal 320 applied to theouter surface of the box. Although not shown, one skilled in the artwould understand that the threaded pin member could be hardfaced insteadof the box. A welding torch 300 powered by a welding power supply 310 isused to melt a hardfacing electrode onto the outer surface of the box.As illustrated by the arrow, the welding torch is moved in the directiontoward the tapered region of the box as the hardfacing metal is appliedto the outer surface of the box. FIG. 7 illustrates that the hardfacingmetal application started at the front end of the box and is progressingtoward the tapered region of the box. The ribbons of hardfacing metalthat are applied to the outer surface of the box are illustrated aspositioned directly adjacent to one another such that the edges of theribbons of hardfacing metal are in contact with one another. The ends ofeach ribbon are slightly stepped over the ends. Such step over is usedto avoid the alignment of any defects that could lead to cracking.

Referring now to FIG. 8 , there is illustrated a work string tubing 200wherein the joint 210 or box has a hardfacing metal 320 applied to theouter surface of the box. Although not shown, one skilled in the artwould understand that the threaded pin member could be hardfaced insteadof the box. A welding torch 300 powered by a welding power supply 310 isused to melt a hardfacing electrode onto the outer surface of the box.As illustrated by the arrow, the welding torch is moved in the directiontoward the tapered region of the box as the hardfacing metal is appliedto the outer surface of the box. FIG. 8 illustrates that the hardfacingmetal application started at the front end of the box and is progressingtoward the tapered region of the box. The ribbons of hardfacing metalthat are applied to the outer surface of the box are illustrated asbeing positioned directly adjacent to one another such that the edges ofthe ribbons of hardfacing metal are on contact with one another. Theapplication of the hardfacing can be applied by using DC polarity(electrode negative). In one non-limiting arrangement, the width of thehardfacing bead applied to the outer surface of the box is about 0.5-2inches (e.g., 1 inch, etc.) and has a thickness of about 0.04-0.3 inches(e.g., 0.094 inches, etc.). As illustrated in FIG. 8 , the applicationof the hardfacing metal to the box results in the outer diameter of thebox being greater than the OEM outer diameter of the box. During theapplication of the hardfacing metal to the outer surface of the box, 1)the electrode can be moved along the longitudinal length and/or aboutthe outer surface of the box or upset portion while the work stringtubing is maintained in position, 2) the electrode can be moved alongthe longitudinal length and/or about the outer surface of the box orupset portion while the work string tubing is rotated and/or moved alongits longitudinal axis, or 3) the electrode can maintained stationarywhile the work string tubing is rotated and/or moved along itslongitudinal axis.

Referring now to FIG. 9 , there is illustrated a work string tubing 200wherein the joint 210 or box has a first layer of hardfacing metal 320and a second layer of hardfacing metal 322 applied to the outer surfaceof the box. Although not shown, one skilled in the art would understandthat the threaded pin member could be hardfaced instead of the box. Awelding torch 300 powered by a welding power supply 310 is used to melta hardfacing electrode onto the outer surface of the box. As illustratedby the arrow, the welding torch is moved in the direction toward thetapered region of the box as the hardfacing metal is applied to theouter surface of the box. FIG. 9 illustrates that the hardfacing metalapplication started at the front end of the box and is progressingtoward the tapered region of the box. The ribbons of hardfacing metalthat are applied to the outer surface of the box are illustrated asbeing positioned directly adjacent to one another such that the edges ofthe ribbons of hardfacing metal are in contact with one another. Theapplication of the hardfacing metal can be applied by using DC polarity(electrode negative). In one non-limiting arrangement, the width of thehardfacing bead applied to the outer surface of the box is about 0.5-2inches (e.g., 1 inch, etc.) and has a thickness of about 0.04-0.3 inches(e.g., 0.094 inches, etc.). The two beads of the hardfacing metal canhave the same or different width and/or thickness. As illustrated inFIG. 9 , the application of the first layer of hardfacing metal to thebox results in the outer diameter of the box being about the same as theOEM outer diameter of the box. The second layer of hardfacing metal isapplied on top of the first layer of hardfacing metal. The hardfacingmetal application for the second layer was also started in a directionfrom the front end of the box toward the tapered region of the box. Theribbons of the second layer of hardfacing metal that are applied to theouter surface of the box are also illustrated as being positioneddirectly adjacent to one another such that the edges of the ribbons ofhardfacing metal are in contact with one another. As can be appreciated,the manner in which the first and second layer of hardfacing metal isapplied to the box can be the same or different. For example, the firstlayer can be applied as illustrated in FIG. 5 or 6 , and the secondlayer can be applied as illustrated in FIG. 4 or 7 , or vice versa. Theapplication of the second layer of hardfacing metal generally results inthe outer diameter of the box being greater than the OEM diameter;however, this is not required. As illustrated in FIG. 9 , the secondlayer of hardfacing metal is only located near the taper portion;however, it can be appreciated that the second layer can be applied tothe complete box region that includes the first layer of hardfacingmetal or at some portion of the box (e.g., front portion, mid region, orrearward region as illustrated in FIG. 9 ). During the application ofthe first and second layers of hardfacing metal to the outer surface ofthe box, 1) the electrode can be moved along the longitudinal lengthand/or about the outer surface of the box or upset portion while thework string tubing is maintained in position, 2) the electrode can bemoved along the longitudinal length and/or about the outer surface ofthe box or upset portion while the work string tubing is rotated and/ormoved along its longitudinal axis, or 3) the electrode can maintainedstationary while the work string tubing is rotated and/or moved alongits longitudinal axis.

The rebuilt work string tube can include a hardfacing as-welded depositof similar or improved strength and/or hardness as the original upsetarea properties of the work string tube; however, this is not required.Generally, the hardfacing metal composition deposited on the surface ofthe work string tube provides improved abrasion- and/or wear-resistanceproperties to the work string tube.

The hardfacing metal composition can be deposited by any suitablewelding means and methods such as, but not limited to, open arc, gas orflux shielded, etc. The welding electrode can be a solid wire, coredelectrode, coated electrode or coated cored electrode. When theelectrode is a coated and/or cored electrode, the coating and/or fillmaterial in the core can include alloying agents, fluxing agents, slagagents, gas generating agents, etc. The electrode can be aself-shielding electrode and/or be used in the presence of a shieldinggas. As such, the hardfacing metal can be applied by a variety ofprocesses such as, but not limited to, submerged arc welding (SAW),shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), gasmetal arc welding (GMAW) or gas tungsten arc welding (TIG).

The hardfacing deposit can be, but is not limited to, Postalloy®Duraband® NC, whose properties generally equal or exceed the originalhardness and strength properties of the original upset properties of thework string tube.

As discussed above, the weld bead of the hardfacing material istypically applied in a direction from the threaded end and progresses tothe tapered end of the box. As such, the threads on the inner surface ofthe box will not be adversely affected (e.g., melted or deformed) duringthe hardfacing process, and openings in the thin walls of the box willnot form during the hardfacing process. By starting the application ofthe hardfacing metal at the threaded end of the box, burn through of thewall of the worn box can be avoided because heat at or near the threadedend of the box can dissipate away from the box via the heat sink of thebody of the work string tube, thereby preventing the temperature of theskin of the box during hardfacing from reaching a temperature sufficientto melt the threads and/or melt though the wall of the box.

The hardfacing deposit can be applied by a non-oscillating process suchthat the weld bead continually progresses forward to form a spiralconfiguration (see FIG. 5 ). The non-oscillating weld progressionincludes the entire area of the upset section. Multiple arc starts aregenerally required to accomplish complete area coverage with thehardfacing material.

The hardfacing deposit can be applied by an oscillating process such as,for example, a ⅜″ wide oscillation (see FIG. 6 ); however, other and/oralternative dimensions may be used.

The hardfacing deposit can include a typical 1″ (or other widths) wideoscillated hardfacing deposit with step-overs occurring at 360° to 370°,producing multiple beads for the length of the upset area (see FIG. 7 );however, this is not required.

The final hardfacing deposit generally has a thickness such that theouter diameter of the box or threaded pin member that includes thehardfacing material has an outer diameter that is generally equal to orslightly greater than the OEM outer diameter of the box or threaded pinmember; however, this is not required.

The final hardfacing deposit generally has a thickness such that theouter diameter of the box or threaded pin member that includes thehardfacing material has an outer diameter that is greater than (proud)the OEM outer diameter of the box or threaded pin member (see FIG. 8 );however, this is not required. The resulting proud hardfacing depositcan be used to provide additional wear resistance to the work stringtube for longer working tube life.

The hardfacing deposit can include a second layer of hardfacing depositthat is located anywhere on the surface of the original upset length.Typically, this deposit is located at or near the tapered region asshown in FIG. 9 ; however, this is not required. During work stringtubing operation, the thicker, two-layer deposit area of the box willwear down first before wear occurs at or near the threaded end of thebox, thereby resulting in longer life of the work string tube.

As illustrated in FIG. 10 , the Duraband® NC (heat affected zone)microhardness values are typically less than Rockwell 30. The heataffect zone is the zone wherein the metal of the OEM box and/or threadedpin member mixes with the composition of the hardfacing metal to createthe bond between hardfacing metal and the box and/or threaded pinmember. These low values will not contribute to any detrimental physicalproperties of the P110 physical properties. As illustrated in FIG. 10 ,the hardness of two tested rows of hardfacing metal applied to a boxand/or threaded pin member of work string tubing formed of P110 alloy isabout 62 Rc (ISO 6508-1). The thickness of the hardfacing metal coatingprior to the heat affected zone was about 0.083 inches. The thickness ofthe heat affected zone was about 0.154 inches. The hardness values dropin the heat affected zone to less than 30 Rc. The lowest hardness valuein the heat affected zone is generally equal to or less than thehardness value of the OEM box and/or threaded pin member. As illustratedin FIG. 10 , the lowest hardness value in the heat affected zone is lessthan the hardness value of the OEM box and/or threaded pin member. Thethickness of the heat affect zone was greater than a thickness of thelayer of hardfacing metal. The minimum hardness of the heat affect zoneis generally less than is less than a hardness of the hardfacing metal.Also, the minimum hardness of the heat affect zone is generally lessthan or equal to a hardness of the box and/or threaded pin member ofwork string tubing.

As illustrated in FIG. 11 , the Postalloy® 2891 (heat affected zone)microhardness values are typically less than Rockwell 30. These lowvalues will not contribute to any detrimental physical properties of theP110 physical properties. As illustrated in FIG. 11 , the hardness oftwo tested rows of hardfacing metal applied to a box and/or threaded pinmember of work string tubing formed of P110 alloy is about 28-33 Rc (ISO6508-1). The thickness of the hardfacing metal coating prior to the heataffected zone was about 0.163 inches. The thickness of the heat affectedzone was about 0.116 inches. The hardness values drop in the heataffected zone to less than 30 Rc. The lowest hardness value in the heataffected zone is generally equal to or less than the hardness value ofthe OEM box and/or threaded pin member. As illustrated in FIG. 11 , thelowest hardness value in the heat affected zone is less than thehardness value of the OEM box and/or threaded pin member. The thicknessof the heat affect zone was less than a thickness of the layer ofhardfacing metal. The minimum hardness of the heat affect zone isgenerally less than is less than a hardness of the hardfacing metal.Also, the minimum hardness of the heat affect zone is generally lessthan or equal to a hardness of the box and/or threaded pin member ofwork string tubing.

As illustrated in FIG. 12 , the Postalloy® 2892 (heat affected zone)microhardness values are typically less than Rockwell 30. These lowvalues will not contribute to any detrimental physical properties of theP110 physical properties. As illustrated in FIG. 12 , the hardness oftwo tested rows of hardfacing metal applied to a box and/or threaded pinmember of work string tubing formed of P110 alloy is about 33-38 Rc (ISO6508-1). The thickness of the hardfacing metal coating prior to the heataffected zone was about 0.143 inches. The thickness of the heat affectedzone was about 0.116 inches. The hardness values drop in the heataffected zone to less than 30 Rc. The lowest hardness value in the heataffected zone is generally equal to or less than the hardness value ofthe OEM box and/or threaded pin member. As illustrated in FIG. 12 , thelowest hardness value in the heat affected zone is less than or aboutequal the hardness value of the OEM box and/or threaded pin member. Thethickness of the heat affect zone is was less than a thickness of thelayer of hardfacing metal. The minimum hardness of the heat affect zoneis generally less than is less than a hardness of the hardfacing metal.Also, the minimum hardness of the heat affect zone is generally lessthan or equal to a hardness of the box and/or threaded pin member ofwork string tubing.

FIG. 13 is a cross-sectional illustration of a prior art work stringtubing connection showing various dimensions of the tubing andconnection, and the specific dimensions of such prior art tubing areprovided as examples in FIGS. 14-15 . These dimensions can be used as ageneral guide to determine how much of the box or threaded pin membercan be removed when repairing the work string tubing. For example, if0.5 inches of the front end of the box is removed, a similar amount ofthe front end of the threaded pin member may need to be removed so thatthe two work string tubings can be properly fit together. Also, if 0.5inches of the front end of the box is removed, the longitudinal lengthof the cavity of the box can be extended by such length so that the twowork string tubings can be properly fit together. As can be appreciated,the amount taken off of the front end of the box and/or threaded pinmember will depend on how worn such regions are and/or to facilitate inthe proper and desired connection with other work string tubing.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompassed by the following claims.

What is claimed is:
 1. A restored worn work string tubing that can bereused in well operations wherein the worn work string tubing is wornsuch that it is no longer approved to be used in the well, said wornwork string tubing comprising a body, a box located at one end of thebody and a threaded pin member having a threaded region located at theother end of the body, said box having a base body with a base outersurface, said base body having a base body front end, a base body backend, a cavity and threads located in said cavity, said threaded pinmember including an upset portion, a rear end of said upset portion isconnected to said body of said work string tubing and has a diameterthat is greater than a diameter of said threaded region of said pinmember, said threaded region of said pin member connected to a front endof said upset portion; said worn work string tubing having been repairedby I) applying a first layer of a hardfacing metal to said base outersurface of said box such that an outer diameter of said box is about90-200% an OEM outer diameter of said box, and wherein said base outersurface has a diameter that is less than 90% of an OEM diameter of saidbox prior to said first layer of said hardfacing metal being applied tosaid base outer surface, and/or II) applying a first layer of ahardfacing metal to an upset outer surface said upset portion of saidthreaded pin member such that an outer diameter of said upset portion isabout 90-200% an OEM outer diameter of said upset portion, wherein saidupset portion of said threaded pin member is less than 90% of an OEMouter diameter of said upset portion prior to said first layer of saidhardfacing metal being applied to said upset portion; and, wherein saidworn work string tubing was repaired by a process that minimizes orprevents a) softening or disfiguring of said box, b) damage to saidthreads in said cavity of said box, c) formation of holes in said box,d) formation of holes in said body of said work string tubing, and/or e)damage to said threaded region of said threaded pin member; and, whereinsaid first layer of said hardfacing metal is applied to said outersurface of said box in a direction from a front end of said box towardsa back end of said box, and/or said first layer of said hardfacing metalis applied to said outer surface of said upset portion of said threadedpin member in a direction from a front end of said upset portion to aback end of said upset portion.
 2. The restored worn work string tubingas defined in claim 1, wherein said first layer of said hardfacing metalcovers 55-100% of said outer surface of said box.
 3. The restored wornwork string tubing as defined in claim 2, wherein a back portion of saidbox includes a tapered region, less than 30% of an outer surface of saidtapered region is covered by said first layer of said hardfacing metalafter said first layer of said hardfacing material is applied to saidouter surface of said box.
 4. The restored worn work string tubing asdefined in claim 3, wherein a second layer of hardfacing metal isapplied to at least a portion of an outer surface of said first layer ofsaid hardfacing metal, said second layer of hardfacing metal has anouter diameter that is 101-200% of said OEM diameter of said box.
 5. Therestored worn work string tubing as defined in claim 4, wherein saidfirst and second layers of said hardfacing metal have a composition ofI) about 0.5-2.5 wt. % carbon, about 0.01-2 wt. % manganese, about0.01-2 wt. % silicon, about 4-11 wt. % chromium, about 3-9 wt. %niobium, and at least about 70 wt. % iron; II) about 0.01-0.25 wt. %carbon, about 0.5-2.5 wt. % manganese, about 0.01-2 wt. % silicon, about1-3.5 wt. % chromium, about 0.01-2 wt. % molybdenum, and at least about85 wt. % iron; or III) about 0.01-1.2 wt. % carbon, about 0.01-1.5 wt. %manganese, about 0.01-1.5 wt. % silicon, about 1.5-4 wt. % chromium,about 0.01-3 wt. % molybdenum, and at least about 85 wt. % iron.
 6. Therestored worn work string tubing as defined in claim 5, wherein saidfirst layer of said hardfacing metal forms a bond with said base outersurface in a heat affect zone, said heat affect zone having a hardnessthat is less than a hardness of said first layer of said hardfacingmetal, a minimum hardness of said heat affect zone is less than or equalto a hardness of said OEM base outer surface.
 7. The restored worn workstring tubing as defined in claim 1, wherein a second layer ofhardfacing metal is applied to at least a portion of an outer surface ofsaid first layer of said hardfacing metal, said second layer ofhardfacing metal has an outer diameter that is 101-200% of said OEMdiameter of said box.
 8. The restored worn work string tubing as definedin claim 1, wherein said first layer of said hardfacing metal has acomposition of I) about 0.5-2.5 wt. % carbon, about 0.01-2 wt. %manganese, about 0.01-2 wt. % silicon, about 4-11 wt. % chromium, about3-9 wt. % niobium, and at least about 70 wt. % iron; II) about 0.01-0.25wt. % carbon, about 0.5-2.5 wt. % manganese, about 0.01-2 wt. % silicon,about 1-3.5 wt. % chromium, about 0.01-2 wt. % molybdenum, and at leastabout 85 wt. % iron; or III) about 0.01-1.2 wt. % carbon, about 0.01-1.5wt. % manganese, about 0.01-1.5 wt. % silicon, about 1.5-4 wt. %chromium, about 0.01-3 wt. % molybdenum, and at least about 85 wt. %iron.
 9. The restored worn work string tubing as defined in claim 1,wherein said first layer of said hardfacing metal forms a bond with saidbase outer surface in a heat affect zone, said heat affect zone having ahardness that is less than a hardness of said first layer of saidhardfacing metal, a minimum hardness of said heat affect zone is lessthan or equal to a hardness of said OEM base outer surface.